Various line detectors for detecting ionizing radiation are known in the art. While such detectors provide for instantaneous one-dimensional imaging, two-dimensional imaging can only be performed by means of scanning the line detector, and optionally the radiation source, in a direction traverse to the one-dimensional detector array. A one-dimensional image is typically recorded each time the line detector, and optionally the radiation source, has been moved a distance corresponding to the width of the radiation sensitive area of the line detector.
Such scanning-based detection is time consuming and may be impractical if large areas should be imaged. Movement of the object being examined may occur during scanning, which could severely reduce the image quality obtained. Thus, the scanning should be made as fast as possible. The exposure, however, has still to be selected such that the images possess high signal-to-noise ratio and high dynamic range.
Further, the spatial resolution is often an important parameter. In many examinations it is desirable to obtain a spatial resolution, which is better than 100 microns, e.g. as good as 50 microns. This put very high demands on the detector being used—both in terms of a narrow radiation sensitive area and in terms of small readout elements or pixels. Alternatively or additionally, very high requirements are put on the radiation source and any collimators employed in order to produce a very thin planar beam of ionizing radiation. For instance, it is extremely difficult—if at all possible—to produce a high quality planar X-ray beam of a thickness of 50 microns and a modest intensity.